Lamination lubricant dispensing unit for lubricating a working roller of a rolling mill for laminating a sheet of alkali metal or alloy thereof into a film

ABSTRACT

A lamination lubricant dispensing unit for lubricating a working roller of a rolling mill for laminating a sheet of alkali metal or alloy thereof into a film. The lubricant dispensing unit has a dispensing unit body defining a laterally extending wall; first and second side walls extending forwardly from the laterally extending wall; and a ledge connected to lower ends of the walls. The ledge extends forwardly from the laterally extending wall and extending between the side walls. The ledge and the walls define a recess having an opened side. The ledge has a front edge for abutting a lamination surface of the working roller. At least a portion of the ledge is an angled portion extending upward and rearward from the front edge toward the laterally extending wall. The dispensing unit body defines at least one lubricant passage having an outlet defined in the laterally extending wall.

CROSS-REFERENCE

This application claims the benefit of U.S. Provisional Application No.62/936,806, filed Nov. 18, 2019, and of U.S. Provisional Application No.62/936,809, filed on Nov. 18, 2019, and U.S. Provisional Application No.62/936,814, filed on Nov. 18, 2019, the disclosure of all of which isincorporated herein by reference in its entirety.

FIELD OF TECHNOLOGY

The present technology relates to lamination lubricant dispensing unitsfor lubricating working roller of rolling mills for laminating sheets ofalkali metal or alloy thereof into films and to rolling mills havingsuch lamination lubricant dispensing units.

BACKGROUND

Rechargeable batteries manufactured from laminates of solid polymerelectrolytes and thin films anodes and cathodes display many advantagesover conventional liquid electrolytes batteries. These advantagesinclude lower overall battery weight, high specific energy, longerservice life, and environmental friendliness since the danger ofspilling toxic liquid into the environment is eliminated.

Solid polymer battery components include positive electrodes, negativeelectrodes and an insulating material capable of permitting ionicconductivity, such as a solid polymer electrolyte sandwiched between theelectrodes. The anodes or negative electrodes are usually made oflightweight metals films, such as alkali metals and alloys thereof, suchas lithium metal, lithium-aluminum alloys and the like. The compositecathodes or positive electrodes are usually formed of a mixture ofactive material such as transitional metal oxide, an electricallyconductive filler, usually carbon particles, an ionically conductivepolymer electrolyte material and a current collector usually a thinsheet of aluminum. Composite cathode thin films are usually obtained bycoating onto a current collector.

The production of thin films of lithium having a thickness lower than100 microns in the form of wide bands, for example 10 centimeters ormore, and in lengths of many hundreds of meters by means of rapid andreliable processes, faces important technical difficulties which areattributable to the extreme physical and chemical properties of thismetal, such as chemical reactivity, malleability, low mechanicalstrength, rapid self-welding by simple contact and strong adhesion onmost solid materials.

Cold extrusion is used for the continuous production of sheets of 100microns or more. These thicknesses are generally adapted to theproduction of lithium cells utilizing liquid electrolytes. For lowerthicknesses, the films obtained by extrusion are thereafter laminatedbetween working rollers made of hard materials.

In large scale production processes, the difficulties in achieving theefficient lamination of dense lithium to a thickness varying between 20and 100 microns for the production of polymer electrolyte cells arenumerous.

The laminated lithium metal often reacts with, and/or deforms, andadheres to the working rollers with which it is in contact during thelamination process. This problem can been solved by the use of alubricating agent as described in U.S. Pat. Nos. 5,837,401, 5,528,920and 6,019,801, the entirety of each of which is incorporated herein byreference. The lubricating agent comprises additives which prevent thethin laminated lithium film from reacting or excessively adhering to theworking rollers and does not effect the electrochemistry of theresulting electrochemical cell. However, there is a desire for a properand efficient application of the lubricant during the laminationprocess.

The extreme ductility of lithium or alloys thereof allows only minusculedrawing tension on the lithium film exiting the working rollers. Thedrawing tension must therefore be precisely monitored and controlled toprevent breakage or ripping of the lithium film and consequently, costlyinterruptions of production.

With a thickness between 20 to 100 microns, it is difficult to laminatea film of lithium or alloy thereof to a constant thickness across theentire width of the film and over extended lengths of the film.Variations of thickness occur across the width of the laminated lithiumfilm in conventional lamination processes which promote breakage of thelithium film during the lamination operation and renders the resultinglaminated lithium film less than adequate for electrochemical cells.

Working rollers are traditionally made of polyacetal, a hard plasticmaterial which is compatible with lithium (i.e. it does not react withlithium). However, for large scale production, the polyacetal rollerswear out rapidly and necessitate frequent replacement and discarding ofthe worn out rollers, thereby drastically increasing cost. This rendersthe lamination manufacturing process economically difficult.

Thus there is a desire for a rolling mill adapted for laminating a sheetof alkali metal or alloy thereof into a film that addresses at leastsome of the above problems. There is also a desire for alkali metalfilms produced by such rolling mills which maintain desirable propertiesover the width and the length of the films.

SUMMARY

It is an object of the present technology to ameliorate at least some ofthe inconveniences present in the prior art.

According to one aspect of the present technology there is provided arolling mill for laminating a sheet of alkali metal or alloy thereofinto a film. The rolling mill has a frame a first working rollerrotationally mounted to the frame, the first working roller having afirst lamination surface; a second working roller rotationally mountedto the frame, the second working roller being disposed below the firstworking roller, the second working roller having a second laminationsurface, the first and second working rollers being positioned toreceive the sheet therebetween; and a lamination lubricant dispensingunit for supplying lubricant onto the second lamination surface. Thelamination lubricant dispensing unit has a dispensing unit body defininga laterally extending wall; first and second side walls extendingforwardly from the laterally extending wall; and a ledge connected to alower end of the laterally extending wall and extending forwardly fromthe laterally extending wall. The ledge is connected to lower ends ofthe first and second side walls and extending between the first andsecond side walls. The ledge, the first and second side walls and thelaterally extending wall define a recess having an opened side. Theledge has a front edge abutting the second lamination surface. At leasta portion of the ledge being an angled portion extending upward andrearward from the front edge toward the laterally extending wall. Thedispensing unit body defines at least one lubricant passage having anoutlet defined in the laterally extending wall. The rolling mill alsohas a lubricant reservoir for holding lamination lubricant therein; anda pump fluidly connected between the lubricant reservoir and the atleast one lubricant passage for supplying lamination lubricant from thelubricant reservoir to the at least one lubricant passage. From theoutlet of the at least one lubricant passage, lamination lubricantflowing along the ledge to the front edge of the ledge and from thefront edge onto the second lamination surface.

According to some aspects of the present technology, the ledge defines alaterally extending gutter in the angled portion of the ledge, thegutter being spaced from the front edge of the ledge.

According to some aspects of the present technology, ends of the gutterare spaced from the first and second side walls.

According to some aspects of the present technology, the front edge ofthe ledge is wider than the second lamination surface.

According to some aspects of the present technology, the at least onelubricant passage is a single lubricant passage.

According to some aspects of the present technology, the outlet of thesingle lubricant passage is laterally centered in the laterallyextending wall.

According to some aspects of the present technology, a bottom of theoutlet of the at least one lubricant passage is vertically aligned withan adjacent portion of the ledge.

According to some aspects of the present technology, a corner betweenthe angled portion of the ledge and the front edge of the ledge isarcuate.

According to some aspects of the present technology, the ledge hasgenerally horizontal portions extending between the angled portion ofthe ledge and the laterally extending wall.

According to some aspects of the present technology, the angled portionis at an angle between 5 and 25 degrees from horizontal.

According to some aspects of the present technology, first and secondworking rollers have a chrome coating at the first and second laminationsurfaces.

According to some aspects of the present technology, the first andsecond lamination surfaces have a surface roughness in a range between0.025 microns Ra and 0.5 microns Ra.

According to some aspects of the present technology, the range isbetween 0.05 microns Ra and 0.3 microns Ra.

According to some aspects of the present technology, a first backuproller is rotationally mounted to the frame. The first backup roller isin contact with the first working roller for applying a pressure on thefirst working roller. A second backup roller is rotationally mounted tothe frame. The second backup roller is in contact with the secondworking roller for applying a pressure on the second working roller.

According to some aspects of the present technology, the laminationlubricant dispensing unit is a second lubricant dispensing unit. Therolling mill also has a first lamination lubricant dispensing unit forsupplying lubricant onto the first lamination surface.

According to some aspects of the present technology, the firstlamination lubricant dispensing unit comprises a plurality of nozzlesfor spraying lamination lubricant onto the first lamination surface.

According to some aspects of the present technology, the front edge ofthe ledge abuts the second lamination surface at a position verticallybelow a central axis of the second working roller.

According to another aspect of the present technology, there is provideda lamination lubricant dispensing unit for lubricating a working rollerof a rolling mill for laminating a sheet of alkali metal or alloythereof into a film. The lubricant dispensing unit has a dispensing unitbody defining a laterally extending wall; first and second side wallsextending forwardly from the laterally extending wall; and a ledgeconnected to a lower end of the laterally extending wall and extendingforwardly from the laterally extending wall. The ledge is connected tolower ends of the first and second side walls and extending between thefirst and second side walls. The ledge, the first and second side wallsand the laterally extending wall define a recess having an opened side.The ledge has a front edge for abutting a lamination surface of theworking roller. At least a portion of the ledge is an angled portionextending upward and rearward from the front edge toward the laterallyextending wall. The dispensing unit body defines at least one lubricantpassage having an outlet defined in the laterally extending wall.

According to some aspects of the present technology, the ledge defines alaterally extending gutter in the angled portion of the ledge, thegutter being spaced from the front edge of the ledge.

According to some aspects of the present technology, ends of the gutterare spaced from the first and second side walls.

According to some aspects of the present technology, the at least onelubricant passage is a single lubricant passage.

According to some aspects of the present technology, the outlet of thesingle lubricant passage is laterally centered in the laterallyextending wall.

According to some aspects of the present technology, a bottom of theoutlet of the at least one lubricant passage is vertically aligned withan adjacent portion of the ledge.

According to some aspects of the present technology, a corner betweenthe angled portion of the ledge and the front edge of the ledge isarcuate.

According to some aspects of the present technology, the ledge hasgenerally horizontal portions extending between the angled portion ofthe ledge and the laterally extending wall.

According to some aspects of the present technology, the angled portionis at an angle between 5 and 25 degrees from horizontal.

For purposes of the present application, surface roughness is providedin Roughness Average (Ra) expressed in metric units, specificallymicrons, and angles are expressed in degrees (i.e. 360 degrees for afull rotation). For purposes of the present application, hardnessrepresents the resistance to localized deformation of a material (e.g.,sheets and films) which deformation is induced by either mechanicalindentation or abrasion. For purposes of the present application,tensile strength (TS) refers to the capacity of a material (e.g., sheetsand films) to resist loads tending to elongate such material. Thetensile strength is measured by the maximum stress that the material canwithstand while being stretched or pulled before breaking.

The term “about” is used herein, explicitly or not; every quantity givenherein is meant to refer to the actual given value, and it is also meantto refer to the approximation to such given value that would reasonablybe inferred based on the ordinary skill in the art, includingequivalents and approximations due to the experimental and/ormeasurement conditions for such given value. For example, the term“about” in the context of a given value or range refers to a value orrange that is within 20%, preferably within 15%, more preferably within10%, more preferably within 9%, more preferably within 8%, morepreferably within 7%, more preferably within 6%, and more preferablywithin 5% of the given value or range.

Embodiments of the present technology each have at least one of theabove-mentioned object and/or aspects, but do not necessarily have allof them. It should be understood that some aspects of the presenttechnology that have resulted from attempting to attain theabove-mentioned object may not satisfy this object and/or may satisfyother objects not specifically recited herein.

Additional and/or alternative features, aspects and advantages ofembodiments of the present technology will become apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present technology, as well as otheraspects and further features thereof, reference is made to the followingdescription which is to be used in conjunction with the accompanyingdrawings, where:

FIG. 1 is a schematic side cross-sectional view of a rolling mill andassociated components for laminating a lithium or lithium alloy sheetinto a thin film;

FIG. 2 is a schematic side elevational view illustrating the maincomponents of the rolling mill of FIG. 1 that enable control of thethickness and shape of the lithium or lithium alloy film beinglaminated;

FIG. 3 is a schematic front elevational view of the main components ofthe rolling mill of FIG. 2;

FIGS. 4A to 4C are schematic front elevational views of backup rollersand working rollers of the rolling mill of FIG. 2 shown in differentadjustments, with angles of frustoconical portions of the workingrollers and the degree of bending of the working rollers having beenexaggerated for illustration purposes;

FIG. 5 is a front elevation view of one working roller of the rollingmill of FIG. 2;

FIG. 6A is a close-up of section 6 of FIG. 5 according to one embodimentof the roller of FIG. 5;

FIG. 6B is a close-up of section 6 of FIG. 5 according to anotherembodiment of the roller of FIG. 5;

FIG. 7 is a schematic cross-sectional profile of the lithium or lithiumalloy sheet supplied to the rolling mill of FIG. 2;

FIG. 8 is a perspective view of a lamination lubricant dispensing unitfor lubricating an upper working roller of the rolling mill of FIG. 1;

FIG. 9 is a perspective view of a lamination lubricant dispensing unitfor lubricating a lower working roller of the rolling mill of FIG. 1;

FIG. 10 is a top plan view of the lamination lubricant dispensing unitof FIG. 9;

FIG. 11 is a front elevation view of the lamination lubricant dispensingunit of FIG. 9;

FIG. 12 is a cross-sectional view of the lamination lubricant dispensingunit of FIG. 9 taken through line 12-12 of FIG. 10; and

FIG. 13 is a close-up of portion 13 of FIG. 12.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a rolling mill 10 and associatedcomponents adapted to produce a lithium or lithium alloy thin film 12 ofless than 100 microns thick from a previously extruded lithium orlithium alloy sheet 14 of about 100 to 500 microns thick. Althoughembodiments of the present technology will be described with respect tothe production of a lithium or lithium alloy thin film 12 from a lithiumor lithium alloy sheet 14, it is contemplated that at least some aspectsof the present technology could be used for the production of otheralkali metal or alkali metal alloy thin films from other alkali metal oralkali metal alloy sheets.

The rolling mill 10 has a main frame 16, a pair of working rollers 18 aand 18 b, a backup roller 20 a adjacent to and in contact with theworking roller 18 a, a backup roller 20 b adjacent to and in contactwith the working roller 18 b, a lamination lubricant dispensing unit 22for dispensing lubricant onto the working roller 18 a and a laminationlubricant dispensing unit 200 for dispensing lubricant onto the workingroller 18 a. As can be seen, the working roller 18 a is disposed belowthe working roller 18 b. The working rollers 18 a, 18 b and thelamination lubricant dispensing units 22, 200 will be described in moredetail below. The working rollers 18 a, 18 b and the backup rollers 20a, 20 b are rotationally mounted on support frames 50 and 52 (FIG. 2) aswill be described in more detail below.

A roll 24 of wound extruded lithium or lithium alloy sheet 14 is placedon a feeding roller 26 comprising an drive motor control unit (notshown) adapted to control the tension of the lithium sheet 14 prior toreaching the working rollers 18 a and 18 b. The sheet 14 snakes its waythrough a series of free rollers 28 leading to an encoder roller 41measuring the exact speed of the traveling sheet 14, and to a tensionroller 43 equipped with a load cell adapted to precisely measure thetension on the sheet 14 entering the lamination apparatus 10. The loadcell of tension roller 43 may be electronically coupled to the controlunit of the drive motor of roll 24 to automatically adjust the tensionexerted onto the sheet 14. The sheet 14 is then fed into a straightener30 which rapidly winds the sheet 14 through a series of tightly packedrollers 32 which has the effect of eliminating lateral displacement ofthe sheet 14 and preventing zigzagging motion of the sheet 14 therebyensuring that the sheet 14 is fed straight into the center portion ofthe working rollers 18 a and 18 b without any lateral weaving motionthat would be detrimental to the lamination process. The sheet 14 istherefore fed into the working rollers 18 a and 18 b at a fixed positionbetween the rollers 18 a, 18 b.

At the inlet of the rolling mill 10, the lubricant dispensing units 22and 200 discharge an adequate amount of lamination lubricant compatiblewith lithium onto the working surfaces of each working roller 18 a and18 b upstream from the lamination area such that the sheet 14 islaminated with properly lubricated working rollers 18 a and 18 b therebypreventing undesirable adhesion of the laminated film 12 onto either onof the working rollers 18 a, 18 b. One suitable lubricant is describedin U.S. Pat. Nos. 5,837,401 and 6,019,801, the entirety of which areincorporated herein by reference. In one embodiment, the lubricant isbased on toluene, hexane and a polyoxyethylene distereate and is used insufficient quantity onto each working roller 18 a and 18 b to preventexcessive adhesion of the laminated film 12 onto either of them.

The sheet 14 passes between the two working rollers 18 a and 18 b whereits thickness is reduced from about 100 to 500 microns to about 20 to100 microns depending on the desired final thickness of the film 12.Pressure is applied by the backup rollers 20 a and 20 b onto the workingrollers 18 a and 18 b which in turn exert pressure on the sheet 14sufficient to reduce its thickness and transform it into a film 12. Thelamination pressure is applied through the backup rollers 20 a and 20 binstead of directly onto the working rollers 18 a and 18 b to help avoidany unwanted bending of the working rollers 18 a and 18 b which would bereflected on the shape and thickness of the film 12. As will bedescribed below, the surface roughness of the working rollers 18 a and18 b should be minimal to produce a thin film 12 of quality. Thepressure applied by the backup rollers 20 a and 20 b onto the workingrollers 18 a and 18 b is evenly distributed on the surfaces of eachroller 18 a and 18 b, thereby leaving the shape of the working rollers18 a and 18 b undisturbed. If however the working rollers 18 a and 18 bare sufficiently rigid, the necessary pressure required to reduce thethickness of the sheet 14 and transform it into the film 12 may beapplied directly by the working rollers 18 a and 18 b without the use ofany backup rollers. It is also contemplated that a plurality of backuprollers could be used to apply even pressure on each of the workingrollers 18 a and 18 b. For instance, two pairs of backup rollers may bepositioned on either side of the working rollers 18 a and 18 b.

The laminated film 12 is pulled through an optical refractory system 36which measures the evenness of the surface of the film 12 and alsodetects any porosity on the film 12 and cracks along the edges of thefilm 12. An optical system can also be used to measure the thickness ofthe film 12. Controlled tension is applied onto the film 12 by a drivenwinding roller 38 to ensure that the film 12 is properly wound. Beforereaching the winding roller 38, the laminated film 12 snakes its wayunder controlled tension through a series of rollers. The first of theserollers is a tension roller 45 equipped with a load cell adapted toprecisely measure the tension on the laminated film 12 exiting therolling mill 10. The load cell of the tension roller 45 may beelectronically coupled to the control unit of the drive motor of thewinding roller 38 to automatically adjust the tension exerted onto thesheet 12. The film 12 then passes over an encoder roller 47 measuringthe exact speed of the traveling film 12. The film 12 then passesthrough a series of free rollers 34 leading to the winding roller 38.

A thin insulating film 90, such as a polypropylene film, is also woundaround the winding roller 38 to separate the layers of film 12 such thatthey will not adhere to each other. The insulating film 90 is pulled bythe winding roller 38 from a roll 92. From the roll 92, the insulatingfilm 90 passes over a tension roller 94 before reaching the roller 38.The tension roller 94 is equipped with a load cell adapted to preciselymeasure the tension on the insulating film 90. This tension measurementis used to control the tension exerted by the winding roller 38 onto thefilm 12 since the tension exerted by the winding roller 38 is dividedbetween the film 12 and the insulating film 90.

The encoder rollers 41 and 47 respectively measure the speed of thesheet 14 entering the rolling mill 10 and the speed of the laminatedfilm 12 exiting the rolling mill 10. The relation between the entryspeed of the sheet 14 and the exit speed of the laminated film 12 isdirectly proportional to the thickness reduction from the initial sheet14 to the film 12. As such, the thickness of the laminated film 12 maybe determined mathematically when the thickness of the initial sheet 14is known. The thickness of the laminated film 12 is thus controlled andverified through the speed differential between the speeds measured bythe encoder rollers 41 and 47. It is contemplated that the thickness ofthe laminated film 12 could be controlled and verified differently.

In one embodiment, the lamination process is carried out in an anhydrideatmosphere containing less than 1% relative humidity to prevent anyunwanted chemical reactions of the lithium film 12 with water particlesthat would render the lithium film 12 unsuitable for use inelectrochemical cells.

Turning now to FIGS. 2 and 3, the main components of the rolling mill 10that enable control of the thickness and shape of the film 12 beinglaminated will be described. It should be understood that theillustrated rolling mill 10 is one exemplary embodiment of a rollingmill adapted to control the shape and thickness of the laminated film 12and that other embodiments are contemplated. For instance, supportmembers and frames may have different configurations, and varioushydraulic system configurations may be used.

The backup rollers 20 a and 20 b are each rotationally mounted onbearings of support frames 50 and 52 respectively. The support frame 52is slidably mounted onto vertical members of the main frame 16 throughany suitable means, such as sliding channels or bearings. The supportframe 50 is fixedly mounted onto the vertical members of the main frame16. The support frame 52 may therefore move vertically. The workingrollers 18 a and 18 b are each driven by electric or hydraulic motors(not shown). The working rollers 18 a, 18 b drive the backup rollers 20a and 20 b by friction. A pair of hydraulic linear actuators 66 ismounted to upper horizontal members of the main frame 16. The hydraulicactuators are connected to the support frame 52. The hydraulic linearactuators 66 control the up and down movements of the support frame 52,as well as the pressure applied onto the working rollers 18 a and 18 b.The working rollers 18 a and 18 b are rotationally mounted ontosupporting members 54 and 56 respectively. The supporting members 54 and56 are operationally linked to the support frames 50 and 52respectively. The end portions 58 and 59 of the supporting members 54are operatively connected to the support frame 50 via a pair ofhydraulic linear actuators 60 and 61 and the end portions 62 and 63 ofsupporting members 56 are operatively connected to the support frame 52via a pair of hydraulic linear actuators 64 and 65.

In operation, the speed of lamination is set by the speed of workingrollers 18 a and 18 b. The pressure P necessary to reduce the thicknessof the film 12 to the desired thickness is adjusted through hydraulicvalves controlling the hydraulic linear actuators 66. The backup roller20 b transfers the pressure P to the working roller 18 b. Once thedesired pressure P is set, the final shape of laminated film 12 isfine-tuned by regulating the fluid pressure to each of the hydrauliclinear actuators 60, 61, 64 and 65 thereby adjusting the forces exertedby each of the hydraulic linear actuators 60, 61, 64 and 65 onto thesupporting members 54 and 56 as will be explained in more detail below.The hydraulic linear actuators 60, 61, 64, 65 and 66 may be replaced byother types of actuators capable of generating sufficient forces, suchas electric actuators. In an alternative embodiment, additionalhydraulic linear actuators are connected between the supporting members54, 56. In such an embodiment, the hydraulic linear actuators 60, 61,64, 65 and 66 are used to push the supporting members 54, 56 toward eachother and the additional hydraulic linear actuators are used to push thesupporting members 54, 56 toward each other.

During the lamination process, heat builds up into the working rollers18 a and 18 b through friction generated at the lamination surfaces withthe effect of slightly dilating the working rollers 18 a and 18 b. Thedilation of the working rollers 18 a, 18 b by a few microns in thelamination zone is enough to produce a film 12 of uneven thickness thatis unsuitable for thin film electrochemical cells. To alleviate thisproblem and help ensure a film 12 of even thickness, the center portions100 (FIG. 4A) of the dilated working rollers 18 a and 18 b is adjustedby bending the working rollers 18 a and 18 b to straighten the centerportions 100 and produce an even thickness lithium film 12. This controlprocess will be described below with respect to FIGS. 4A to 4C. Notethat the shapes of the working rollers 18 a and 18 b illustrated inFIGS. 4A to 4C are greatly exaggerated for the sake of clarity, but itshould be understood that the tapering of the end portions of theworking rollers 18 a, 18 b and the bent profiles are in fact not visibleto the naked eye as they represent mere microns of deviations from aperfectly linear profile.

FIG. 4A illustrates the working rollers 18 a and 18 b in a neutralposition. The backup rollers 20 a and 20 b apply a pressure P onto theworking rollers 18 a and 18 b sufficient to reduce the thickness of thesheet 14 to the desired thickness of film 12 while no lateral force isapplied to the supporting members 54 and 56 of the working rollers 18 a,18 b.

In FIG. 4b , the backup rollers 20 a and 20 b still apply a pressure Ponto the working rollers 18 a and 18 b sufficient to reduce thethickness of the sheet 14 to the desired thickness of film 12. However,due to thermal dilation, the center portion of the working rollers 18 aand 18 b have expanded through heat build-up generated by friction ofthe center portions 100 against the sheet 14. To compensate this heatdilation which has deformed the working rollers 18 a and 18 b, inwardlyoriented lateral forces Fx are applied to the supporting members 54 and56. The lateral forces Fx slightly bend the working rollers 18 a and 18b outwardly, thereby flattening the center portions 100 as depicted inFIG. 4B. The outside edges of the working rollers 18 a and 18 b are bentinwardly to straighten the center portions 100. The resulting laminatedfilm 12 will therefore be flat and have an even thickness. Thermaldilation of the working rollers 18 a, 18 b is also partly counteractedby the application of the lamination lubricant onto the working rollers18 a, 18 b. It is also contemplated that additional means of cooling theworking rollers 18 a, 18 b could be used to help counteract the thermaldilation of the working rollers 18 a, 18 b.

When the edges of the sheet 14 being laminated are thicker than itscentral portion, in order to laminate a film 12 having an even thicknessthroughout its width, more pressure is to be applied by the workingrollers 18 a and 18 b to the outside edges of the sheet 14 and thereforeto the outer edges of the center portions 100. To do so, the samelateral forces Fx are applied to the supporting members 54 and 56thereby slightly bending the outer edges of the working rollers 18 a and18 b inwardly, and applying more pressure to the edges of the sheet 14than to its central portion. As a result, the laminated film 12 has aneven thickness throughout its width. As heat builds-up in the workingrollers 18 a and 18 b through friction of the center portions 100against the sheet 14, the center portions of the working rollers 18 aand 18 b dilate marginally. To compensate for this heat dilation whichis marginally increasing the diameters of the center portions of theworking rollers 18 a and 18 b, the lateral forces Fx are proportionallyreduced to maintain the center portions 100 straight such that theresulting laminated film 12 will have an even thickness throughout itsentire width.

At times, the central portion of the sheet 14 being laminated can bethicker than its edges. In order to laminate a film 12 having an eventhickness throughout its width, more pressure must be applied by theworking rollers 18 a and 18 b onto the central portion of the sheet 14and therefore to the central portions of center portions 100. As shownin FIG. 4c , to do so, outwardly oriented lateral forces Fy are appliedto the supporting members 54 and 56. The lateral forces Fy slightly bendthe central portion of the working rollers 18 a and 18 b inwardlyforcing the central portions of the center portions 100 inwardly therebyapplying more pressure onto the central portion of the sheet 14 andlaminating a film 12 having an even thickness throughout its entirewidth.

In some circumstances, heat generated by the friction of the centerportions 100 against the sheet 14 will build up in the outside portionsof the meeting surfaces of working rollers 18 a and 18 b and dilatethem, opening a small gap in the central portion of the center portions100. To compensate this heat dilation, outwardly oriented lateral forcesFy are applied to the supporting members 54 and 56 of the workingrollers 18 a and 18 b. The lateral forces Fy slightly bend the centralportion of the center portions 100 inwardly and straightening centerportions 100. The profiles of the center portions 100 of the workingrollers 18 a, 18 b are bent back into straight lines such that theresulting laminated film 12 will be flat and have an even thicknessthroughout its entire width.

Although only symmetrical adjustments of the working rollers 18 a, 18 bhave been shown in FIGS. 4B and 4C, because the supporting members 54and 56 are independent from each other, other adjustments are possible.For instance, if the working rollers 18 a, 18 b dilate more on one sidethan the other, the left or the right supporting members 54, 56 may havea force Fx or Fy exceeding the force Fx or Fy of the supporting members54, 56 on the opposite side such that a multitude of fine tuningadjustments are possible.

The adjustments of the shape of center portions 100 combined with theprecise measurements of an adequate measuring device such as the opticalrefractory system 36 enables the rolling mill 10 to produce a laminatedfilm 12 of quality in the range of thickness from 20 to 100 microns thatexhibits a near constant thickness throughout its entire length andwidth.

The adjustments of the profile and thickness of laminated film 12 mayeither be performed by an operator on site that fine tunes the pressuresapplied by backup rollers 20 a and 20 b and the pressures applied to thesupporting members 54 and 56 or this task may be performedelectronically by linking the measurement readings and the actuatorscontrolling the various pressures and forces of the backup rollers 20 a,20 b and the working rollers 18 a, 18 b to a computer providingreal-time adjustments of theses parameters.

Turning now to FIGS. 5 to 6B, the working roller 18 a will be describedin more detail. In the present embodiment, the working roller 18 b isidentical to the working roller 18 a, as such the working roller 18 bwill not be separately described herein. It is contemplated that theworking roller 18 b could differ in part from the working roller 18 a.

As previously mentioned, the working roller 18 a has a center portion100. The center portion 100 is a cylindrical center portion 100. Anouter surface 102 of the center portion 100 defines a lamination surfacewhich rolls over the sheet 14 during the lamination process. As such,the center portion 100 has a width W1 that is slightly wider than awidth W2 (FIG. 7) of the sheet 14 to be laminated. The center portion100 defines a central axis 104 of the working roller 18 a.

Frustoconical portions 106 extend from the ends of the center portion100. The frustoconical portions 106 are mirror images of each other. InFIG. 5 the outer surfaces 110 of the frustoconical portions 106 do notappear to taper. This is because the tapering angle is very small and isnot visible to the naked eye. This angle has been exaggerated in FIGS.6A and 6B which illustrate two different embodiments of the workingroller 18 a and will be described below. Each frustoconical portion 106has a width W3. The width W1 of the center portion 100 is greater thanthe width W3 of each frustoconical portion 106. The width W1 of thecenter portion 100 is less than a sum of the widths W3 of bothfrustoconical portions 106 (i.e. W1<W3+W3). In some embodiment, thewidth W1 is between 125 mm and 210 mm and the width W3 is between 65 mmand 110 mm.

In one embodiment illustrated in FIG. 6A, the frustoconical portions 106taper as they extend away from the center portion 100. This embodimentis the one shown in FIGS. 4A to 4C where the tapering has beenexaggerated. In this embodiment, shoulders 108 are defined between thecenter portion 100 and each frustoconical portion 106 (shown for onefrustoconical portion in FIG. 6A). In some embodiments, the shoulders108 have a height H1 that is less than 0.05 mm. In some embodiments, theheight H1 is less than 0.02 mm. It is contemplated that the shoulders108 could be omitted. When the central axis 104 is straight (i.e. whenthe working roller 18 a is in the neutral position as in FIG. 4A), anangle A between the outer surface 102 of the center portion 100 and anouter surface 110 of the frustoconical portion 106 is less than 0.05degrees. In some embodiment, the angle A is less than 0.03 degrees. Insome embodiments, the angle A is less than 0.02 degrees. In someembodiments, the angle A is less than 0.02 degrees but more than 0.01degrees. In some embodiments, the center portion 100 has a diameter D1between 70 mm and 90 mm. In some embodiments, a difference between thesmallest diameter D2 and the greatest diameter D3 of each frustoconicalportion 106 is between 0.03 mm and 0.17 mm. The profiles of the workingrollers 18 a and 18 b according to this embodiment facilitate theirbending by providing free zones 84 (FIG. 4A) between the frustoconicalportions 106 and free zones 85 (FIG. 4A) between the frustoconicalportions 106 and the backup rollers 20 a and 20 b such that the ends ofthe working rollers 18 a and 18 b may be moved to bend the centerportions 100 as desired. The free zones 84 also allow excess laminationlubricant to be evacuated laterally during the lamination process.Although the working roller 18 a of the embodiment shown in FIG. 6Acould be used with a sheet 14 having many different profiles thanks tothe adjustments that can be made in the rolling mill 10 (as discussedabove with respect to FIGS. 4A to 4C), this embodiment of the workingroller 18 a is particularly well suited for laminating a sheet 14 whichhas been extruded with a central portion 112 having a height H2 (FIG. 7)that is smaller than a height H3 of its side portions 114 (FIG. 7).Again, in FIG. 7 the heights H2 and H3 do not appear to be differentbecause the difference is not visible to the naked eye. In someembodiments, the height H2 is less than 15 microns smaller that theheight H3.

In another embodiment illustrated in FIG. 6B, each frustoconicalportions 106 tapers as is extends from its outer end toward the centerportion 100 (i.e. D2 is greater than D3). When the central axis 104 isstraight (i.e. when the working roller 18 a is in the neutral position),an angle B between the outer surface 102 of the center portion 100 andan outer surface 110 of the frustoconical portion 106 is less than 0.05degrees. In some embodiment, the angle B is less than 0.03 degrees. Insome embodiments, the angle B is less than 0.02 degrees. In someembodiments, the angle B is less than 0.02 degrees but more than 0.01degrees. In some embodiments, the center portion 100 has a diameter D1between 70 mm and 90 mm. In some embodiments, a difference between thegreatest diameter D2 and the smallest diameter D3 of each frustoconicalportion 106 is between 0.03 mm and 0.17 mm. Although the working roller18 a of the embodiment shown in FIG. 6B could be used with a sheet 14having many different profiles thanks to the adjustments that can bemade in the rolling mill 10 (as discussed above with respect to FIGS. 4Ato 4C), this embodiment of the working roller 18 a is particularly wellsuited for laminating a sheet 14 which has been extruded with a centralportion 112 having a height H2 (FIG. 7) that is greater than a height H3of its side portions 114 (FIG. 7). In some embodiments, the height H2 isless than 15 microns bigger that the height H3.

Returning to FIG. 5, the working roller 18 a has support shafts 116, 118extending from the ends of the frustoconical portions 106. The supportsshafts 116, 118 are received in bearings (not shown) for rotationallymounting the working roller 18 a to the supporting members 54 (or to thesupporting members 56 for the working roller 18 b). The support shaft118 has an extension 120 adapted for connection to the motor driving theworking roller 18 b. The portions 100, 106, and the support shafts 116,118 are integrally formed.

As previously mentioned, the lamination lubricant dispensed onto theworking rollers 18 a and 18 b helps prevent adhesion of the lithium film12 onto the working rollers 18 a, 18 b such that the film 12 exits theworking rollers 18 a and 18 b in a straight line. The use of lubricantenables to laminate lithium and lithium alloys with the working rollers18 a, 18 b made of material that would normally not be adequate becauseof their adhesion to lithium. The lubricant negates this restriction.Therefore, for large-scale production, the working rollers 18 a, 18 bare preferably made of durable hard material such as steel or stainlesssteel or even ceramic. In some embodiments, the steel or stainless steelrollers 18 a, 18 b have a thin chrome coating for added hardness. Thechrome coating is applied at least on the center and frustoconicalportions 100, 106 of the working rollers 18 a, 18 b. In someembodiments, the chrome coating is a hard chrome coating. In order toprovide the desired surface finish for the film 12 and to permit someadherence of the lamination lubricant onto the working rollers 18 a, 18b, in some embodiments the outer surfaces 102, 110 of the center andfrustoconical portions 100, 106 have a surface roughness in a rangebetween 0.025 microns Ra and 0.5 microns Ra. In other embodiments, thesurface roughness is in a range between 0.05 microns Ra and 0.30 micronsRa

Turning now to FIG. 8, the lamination lubricant dispensing unit 22 willbe described in more detail. The lamination lubricant dispensing unit 22includes four nozzles 150 mounted to a rail 152. It is contemplated thatthe lamination lubricant dispensing unit 22 could have more or less thanfour nozzles 150. Lamination lubricant is supplied to a passage (notshown) inside the rail 152 via an intake connector 154. The intakeconnector 154 is fluidly connected to a pump (not shown) that supplieslubricant to the intake connector 154 from a lubricant reservoir (notshown) holding the lamination lubricant therein. The four nozzles 150fluidly communicate with the passage inside the rail 152. As can be seenin FIG. 1, the lamination lubricant dispensing unit 22 is disposedupstream of the lamination area and is spaced from the working roller 18b. The lamination lubricant dispensing unit 22 is disposed above thecentral axis 104 of the working roller 18 b and is angled such that thenozzles 150 continuously spray lamination lubricant on the laminationsurface of the working roller 18 b. The sprays from the nozzles 150cover an area slightly wider than the lamination surface.

Each nozzle 150 has a nozzle body 156, a filter, a nozzle head 158 and anut 160. The nozzle body 156 is threaded into the rail 152. The filteris disposed inside the nozzle body 156. The nozzle head 158 defines aspray aperture 162 and is disposed on the end of the nozzle body 156.The nut 160 is disposed over the nozzle body 156 and is threaded ontothe nozzle body 156 to maintain the nozzle head 158 and the filter inposition.

Turning now to FIGS. 9 to 13, the lamination lubricant dispensing unit200 will be described. In the present embodiment, the laminationlubricant dispensing unit 200 is made from a single piece ofstatic-dissipative acetal copolymer. It is contemplated that other typesof materials could be used such as polyamide, polypropylene,polyethylene, acrylonitrile butadiene styrene, polyethyleneterephthalate, polystyrene, thermoplastic polyurethane, poly(methylmethacrylate), polyvinyl chloride, brass and aluminum for example. Othermaterials are also contemplated. It is also contemplated that thelamination lubricant dispensing unit 200 could be made from multipleparts bonded or otherwise connected to each other.

The lamination lubricant dispensing unit 200 has a dispensing unit body202. Each rear corner portion of the dispensing unit body 202 definestwo apertures 206. Fasteners (not shown) are received in the apertures206 to fasten the dispensing unit body 202 to the frame 16 of therolling mill 10 at a position between the working roller 18 a and thestraightener 30. The dispensing unit body 202 defines a laterallyextending wall 208. A single lubricant passage 210 is defined in thedispensing unit body 202 as best seen in FIG. 12. The lubricant passage210 has an inlet (not shown) defined in a rear wall 214 of thedispensing unit body 202 and an outlet 216 defined in the laterallyextending wall 208. As can be seen, the outlet 216 is laterally centeredin the laterally extending wall 208 and is disposed at a bottom thereof.It is contemplated that multiple lubricant passages 210 could be definedin the dispensing unit body 202, with the outlets of these passagesbeing at different positions along the laterally extending wall 208. Itis also contemplated that at least some of these multiple lubricantpassages 210 could have a common inlet.

Two side walls 218 extend forwardly from the laterally extending wall208. As can be seen in FIG. 10, the side walls 218 are parallel to eachother. As can be seen in FIG. 12, the front ends 220 of the side walls218 are angled from vertical so as to not interfere with the workingroller 18 a.

The lamination lubricant dispensing unit 200 also has a ledge 222. Theledge 222 is connected to the lower end of the laterally extending wall208 and extends forwardly therefrom. The ledge 222 is also connected tothe lower ends of the side walls 218 and extends therebetween. The ledge222, the side walls 218 and the laterally extending wall 208 togetherdefine a recess 224 having an opened side at a front of the laminationlubricant dispensing unit 200. The ledge 222 has a front edge 226 thatabuts the lamination surface of the working roller 18 a at a positionvertically below the central axis 104 of the working roller 18 a, as canbe seen in FIG. 12. The front edge 226 has a width W4 (FIG. 10) that isgreater than the width W1 of the lamination surface of the workingroller 18 a to help ensure that lamination lubricant will be appliedacross and entire width of the lamination surface.

With reference to FIG. 13, the ledge 222 has an angled portion 228 thatextends upward and rearward from the front edge 226 toward the laterallyextending wall 208. The corner 230 between the angled portion 228 andthe front edge 226 is arcuate. In some embodiments, the angled portion228 extends at an angle C between 5 and 25 degrees from horizontal. Insome embodiments, the angle C is between 10 and 20 degrees fromhorizontal. The ledge 222 also has a generally horizontal portion 232extending between the angled portion 228 and the laterally extendingwall 208. The portion 232 is horizontal when viewed from the side (i.e.as viewed in FIGS. 12 and 13). However, from a front view of the portion232 (i.e. as viewed in FIG. 11), the portion 232 slopes slightlydownward on both sides of its lateral center, which thereforecorresponds to the apex of the portion 232. In some embodiments, theangle D (FIG. 11) between the surfaces on both sides of the lateralcenter of the portion 232 is greater than 180 degrees but less than 185degrees, and in some embodiments less than 182 degrees. It is alsocontemplated that the portion 232 could also be flat (i.e. angle D being180 degrees) as viewed from the front view of the portion 232 (i.e. asviewed in FIG. 11). As can be seen in FIGS. 11 and 12, the outlet 216 ofthe lubricant passage 210 is laterally aligned with the apex of theportion 232 and the bottom of the outlet 216 is vertically aligned withthe top of the portion 232 of the ledge 222 adjacent to it. It iscontemplated that the portion 232 could be omitted and that the angledportion 228 could extend from the front edge 226 to the laterallyextending wall 208.

A laterally extending gutter 234 is defined in the angled portion 228 ofthe ledge 222. As best seen in FIG. 10, the ends of the gutter 234 arespaced from the side walls 218. The gutter 234 is spaced from the frontedge 226 of the ledge 222. As can be seen in FIG. 13, the gutter 234 iscloser to the front edge 226 than to the portion 232 of the ledge 222.

With reference to FIG. 12, the inlet of the lubricant passage 210 isfluidly connected to a pump 236, which is itself fluidly connected to alubricant reservoir 238. The lubricant reservoir 238 holds thelamination lubricant therein. It is contemplated that the lubricantreservoir 238 could also be used for supplying the lamination lubricantto the lamination lubricant dispensing unit 22 described above. The pump236 pumps lamination fluid from the lubricant reservoir 238 into thelubricant passage 210. From the outlet 216 of the lubricant passage 210,the lubricant flows forward and laterally (due to angle D) along theportion 232 of the ledge. The lubricant then flows down along the angledportion 228. Some of the lubricant will flow into the gutter 234 whichhelps ensure an even distribution of lubricant across a width of theledge 222. The lubricant then flows to the front edge 226 where it makescontact with the lamination surface of the working roller 18 a. Theupwardly moving lamination surface of the working roller 18 a picks uplubricant which effectively coats the lamination surface that will makecontact with the sheet 14.

In some embodiments, the alkali metal or alkali metal alloy film of thepresent technology is a laminated lithium film or a laminated lithiumalloy film obtained using the rolling mill and working rollers asdefined herein.

The lithium alloys that may be used to prepare the films of the presenttechnology include, but are not limited to: Lithium-Silicon,Lithium-Aluminum, Lithium-Magnesium, Lithium-Strontium, Lithium-Bariumand the like.

The lithium or lithium alloy films of the present technology comprise anamount of metallic element. The addition of a metallic element to thelithium or lithium alloy films allows to decrease the overall thicknessof the film and to improve its overall mechanical strength. In someinstances, the metallic element is present in the lithium or lithiumalloy film in an amount that improves the mechanical strength throughoutthe width, thickness and length of the film.

The metallic element that may be used in the preparation of the lithiumor lithium alloy films of the present technology is preferablyelectrically conductive. It is to be understood that the presence of themetallic element should not impede the electrical conductivity of thelithium or lithium alloy film. For example, aluminum is a metallicelement that can be used in the lithium or lithium alloy film. In someinstances, aluminum is present in the film in an amount ranging betweenabout 3000 ppm and about 10 000 ppm, or between about 3000 ppm and about9000 ppm, or between about 3000 ppm and about 8000 ppm, or between about3000 ppm and about 7000 ppm, or between about 3000 ppm and about 6000ppm, or between about 3000 ppm and about 5000 ppm. In some instances,aluminum is present in the film in an amount that is equal to or greaterthan 3000 ppm.

In some instances, the lithium or lithium alloy film of the presenttechnology has a hardness as measured by a Shore durometer (Shore Ascale) that ranges between about 50 and about 85, or between about 60and about 80, or between about 60 and about 75, or between about 50 andabout 70, or between about 60 and about 75, or between about 65 andabout 75, or between about 66 and 70, or between about 66 and 69. Insome instances, the hardness is of at least 65. In some other instances,the hardness is of at least about 66. In some instances, the hardness iseven throughout the entire lithium or lithium alloy film.

The lithium film obtained by the technology defined herein has a width(which corresponds to the distance from one edge of the film to theother) that ranges between about 140 mm and about 200 mm, or betweenabout 150 mm and about 200 mm, or between about 160 mm and about 180 mm,or between about 160 mm and about 175 mm, or between about 160 mm andabout 170 mm, or between about 160 mm and 165 mm and has a thicknessthat ranges between about 20 microns and about 100 microns, or between20 microns and about 90 microns, or between about 20 microns and about75 microns, or between about 20 microns and about 50 microns, or betweenabout 20 microns and 30 microns. The thickness of the lithium or lithiumalloy film is even throughout the entire width of the film. Thethickness being even throughout the entire width of the film encompassesa variation in thickness of about +/−2 microns.

In some embodiments, the lithium or lithium alloy films obtained by thetechnology defined herein have a thickness to width (t/w) ratio that isbetween about 1×10⁻⁴ and about 7×10⁻⁴. In some instances, this t/w ratiois maintained throughout the entire length of the film.

In particular, the present technology allows to maintain the width,thickness and hardness of the lithium or lithium alloy films even overextended film lengths. For example, the lithium or lithium alloy film ofthe present technology maintains its width, thickness and hardness overat least about 15000 meters, over at least about 10000 meters, over atleast about 9000 meters, over at least 8000 meters, over at least 7000meters, over at least 6000 meters, over at least 5000 meters, over atleast 4000 meters, over at least 3000 meters, over at least 2000 meters,or over at least over 1000 meters.

EXAMPLES

The examples below are given so as to illustrate the practice of variousembodiments of the present technology. They are not intended to limit ordefine the entire scope of this technology. It should be appreciatedthat the technology is not limited to the particular embodimentsdescribed and illustrated herein but includes all modifications andvariations falling within the scope of the disclosure as defined in theappended embodiments.

Example 1—Production of a Laminated Lithium Alloy Film (3000 ppm)

A laminated lithium film was prepared using a rolling mill comprisingthe working rollers as defined herein. The lithium film obtained had awidth of 170 mm, a thickness of 60 microns and an aluminum content of3000 ppm. Hardness of the film was assessed using a Shore durometer (PTCmodel 320—A Scale). The results are presented in Table 1.

TABLE 1 Hardness of a laminated LiAl film (3000 ppm Al) Sample Hardness(Shore A) 1 66 2 66 3 66 4 66 5 66

Example 2—Production of a Laminated Lithium Alloy Film (5000 ppm)

A laminated lithium film was prepared using a rolling mill comprisingthe working rollers as defined herein. The lithium film obtained had awidth of 170 mm, a thickness of 60 microns and an aluminum content of5000 ppm. Hardness of the film was assessed using a Shore durometer (PTCmodel 320—A Scale). The results are presented in Table 2.

TABLE 2 Hardness of a LiAl film (5000 ppm Al) Sample Hardness (Shore A)1 68 2 69 3 68 4 68 5 67

Example 3—Assessing Tensile Strength of Laminated Lithium Alloy Film(3000 ppm)

A laminated lithium-aluminum film was prepared using a rolling millcomprising the working rollers as defined herein. The lithium film had awidth of 170 mm, a thickness of 60 microns and an aluminum content of3000 ppm. Tensile strength of the lithium film was assessed using atestometric M500 25 kN. The results are presented in Table 3.

TABLE 3 Tensile Strength of LiAl film (3000 ppm Al) at 10 mm/min SampleUTS kgf/cm² UTS mpa 1 20.23 1.98 2 19.56 1.91 3 19.57 1.91 4 21.08 2.065 19.98 1.96

Example 4—Assessing Tensile Strength of Laminated Lithium Alloy Film(5000 ppm)

A laminated lithium-aluminum film was prepared using a rolling millcomprising the working rollers as defined herein. The lithium film had awidth of 170 mm, a thickness of 60 microns and an aluminum content of5000 ppm. Tensile strength of the lithium film was assessed using atestometric M500 25 kN. The results are presented in Table 4.

TABLE 4 Tensile Strength of LiAl film (5000 ppm Al) at 10 mm/min SampleUTS kgf/cm² UTS mpa 1 23.41 2.30 2 22.52 2.20 3 22.63 2.21 4 23.47 2.305 23.28 2.28

Modifications and improvements to the above-described embodiments of thepresent technology may become apparent to those skilled in the art. Theforegoing description is intended to be exemplary rather than limiting.The scope of the present technology is therefore intended to be limitedsolely by the scope of the appended claims.

What is claimed is:
 1. A rolling mill for laminating a sheet of alkalimetal or alloy thereof into a film, the rolling mill comprising: a framea first working roller rotationally mounted to the frame, the firstworking roller having a first lamination surface; a second workingroller rotationally mounted to the frame, the second working rollerbeing disposed below the first working roller, the second working rollerhaving a second lamination surface, the first and second working rollersbeing positioned to receive the sheet therebetween; a laminationlubricant dispensing unit for supplying lubricant onto the secondlamination surface, the lamination lubricant dispensing unit comprising:a dispensing unit body defining a laterally extending wall; first andsecond side walls extending forwardly from the laterally extending wall;and a ledge connected to a lower end of the laterally extending wall andextending forwardly from the laterally extending wall, the ledge beingconnected to lower ends of the first and second side walls and extendingbetween the first and second side walls, the ledge, the first and secondside walls and the laterally extending wall defining a recess having anopened side, the ledge having a front edge abutting the secondlamination surface, at least a portion of the ledge being an angledportion extending upward and rearward from the front edge toward thelaterally extending wall, the dispensing unit body defining at least onelubricant passage having an outlet defined in the laterally extendingwall; a lubricant reservoir for holding lamination lubricant therein;and a pump fluidly connected between the lubricant reservoir and the atleast one lubricant passage for supplying lamination lubricant from thelubricant reservoir to the at least one lubricant passage, from theoutlet of the at least one lubricant passage, lamination lubricantflowing along the ledge to the front edge of the ledge and from thefront edge onto the second lamination surface.
 2. The rolling mill ofclaim 1, wherein the ledge defines a laterally extending gutter in theangled portion of the ledge, the gutter being spaced from the front edgeof the ledge.
 3. The rolling mill of claim 2, wherein ends of the gutterare spaced from the first and second side walls.
 4. The rolling mill ofclaim 1, wherein the front edge of the ledge is wider than the secondlamination surface.
 5. The rolling mill of claim 1, wherein the at leastone lubricant passage is a single lubricant passage.
 6. The rolling millof claim 5, wherein the outlet of the single lubricant passage islaterally centered in the laterally extending wall.
 7. The rolling millof claim 1, wherein a bottom of the outlet of the at least one lubricantpassage is vertically aligned with an adjacent portion of the ledge. 8.The rolling mill of claim 1, wherein a corner between the angled portionof the ledge and the front edge of the ledge is arcuate.
 9. The rollingmill of claim 1, wherein the ledge has generally horizontal portionsextending between the angled portion of the ledge and the laterallyextending wall.
 10. The rolling mill of claim 1, wherein the angledportion is at an angle between 5 and 25 degrees from horizontal.
 11. Therolling mill of claim 1, wherein first and second working rollers have achrome coating at the first and second lamination surfaces.
 12. Therolling mill of claim 1, wherein the first and second laminationsurfaces have a surface roughness in a range between 0.025 microns Raand 0.5 microns Ra.
 13. The rolling mill of claim 12, wherein the rangeis between 0.05 microns Ra and 0.3 microns Ra.
 14. The rolling mill ofclaim 1, further comprising: a first backup roller rotationally mountedto the frame, the first backup roller being in contact with the firstworking roller for applying a pressure on the first working roller; anda second backup roller rotationally mounted to the frame, the secondbackup roller being in contact with the second working roller forapplying a pressure on the second working roller.
 15. The rolling millof claim 1, wherein the lamination lubricant dispensing unit is a secondlubricant dispensing unit; and the rolling mill further comprises afirst lamination lubricant dispensing unit for supplying lubricant ontothe first lamination surface.
 16. The rolling mill of claim 15, whereinthe first lamination lubricant dispensing unit comprises a plurality ofnozzles for spraying lamination lubricant onto the first laminationsurface.
 17. The rolling mill of claim 1, wherein the front edge of theledge abuts the second lamination surface at a position vertically belowa central axis of the second working roller.
 18. A lamination lubricantdispensing unit for lubricating a working roller of a rolling mill forlaminating a sheet of alkali metal or alloy thereof into a film, thelubricant dispensing unit comprising: a dispensing unit body defining alaterally extending wall; first and second side walls extendingforwardly from the laterally extending wall; and a ledge connected to alower end of the laterally extending wall and extending forwardly fromthe laterally extending wall, the ledge being connected to lower ends ofthe first and second side walls and extending between the first andsecond side walls, the ledge, the first and second side walls and thelaterally extending wall defining a recess having an opened side, theledge having a front edge for abutting a lamination surface of theworking roller, at least a portion of the ledge being an angled portionextending upward and rearward from the front edge toward the laterallyextending wall, and the dispensing unit body defining at least onelubricant passage having an outlet defined in the laterally extendingwall.
 19. The lamination lubricant dispensing unit of claim 18, whereinthe ledge defines a laterally extending gutter in the angled portion ofthe ledge, the gutter being spaced from the front edge of the ledge. 20.The lamination lubricant dispensing unit of claim 19, wherein ends ofthe gutter are spaced from the first and second side walls.
 21. Thelamination lubricant dispensing unit of claim 18, wherein the at leastone lubricant passage is a single lubricant passage.
 22. The laminationlubricant dispensing unit of claim 21, wherein the outlet of the singlelubricant passage is laterally centered in the laterally extending wall.23. The lamination lubricant dispensing unit of claim 18, wherein abottom of the outlet of the at least one lubricant passage is verticallyaligned with an adjacent portion of the ledge.
 24. The laminationlubricant dispensing unit of claim 18, wherein a corner between theangled portion of the ledge and the front edge of the ledge is arcuate.25. The lamination lubricant dispensing unit of claim 18, wherein theledge has generally horizontal portions extending between the angledportion of the ledge and the laterally extending wall.
 26. Thelamination lubricant dispensing unit of claim 18, wherein the angledportion is at an angle between 5 and 25 degrees from horizontal.